The present invention is directed to bulk bag dischargers for discharging dry flowable materials from flexible intermediate bulk bags, and more particularly to an improved discharge chute for use in such dischargers.
Bulk bag dischargers typically include a frame for supporting an intermediate bulk bag containing dry flowable material in vertical orientation with a discharge opening of the bag disposed at the lower end of the suspended bag. A downwardly and inwardly tapering discharge chute is carried by the frame for receiving the lower end of the bag and guiding material discharged from the bag to a lower outlet end of the chute. Among the objects of the present invention are to provide a bulk bag discharger, and particularly a discharge chute, that is fabricated at reduced cost as compared with the prior art, that exhibits a reduced likelihood of blockage by flowable material during use, that exhibits increased operating life, and/or that maybe readily modified by a user in the field to provide a discharge opening of a desired size.
In accordance with one aspect of the present invention, a discharge chute for a bulk bag discharger of the type described above is fabricated of plastic, preferably molded plastic. The chute has an upper portion for securement to the bulk bag discharger frame, such that the mid and lower portions of the chute are freely suspended from the frame. The mid portion of the chute includes one flat sidewall and three elliptical sidewalls. A door is provided in the flat sidewall of the chute for affording operator access to the interior of the chute to untie a bag discharge, for example. A vibrator is mounted on a vibrator mounting plate on one of the elliptical sidewalls of the chute. The lower end of the chute forms a circular outlet opening, and preferably is of stepped configuration so that an operator may selectively remove steps from the outlet end of the chute to provide an outlet opening of desired diameter.
The plastic construction of the chute reduces fabrication cost, and facilitates operator modification of the chute outlet opening to the desired outlet opening diameter. Molded plastic construction of the chute also eliminates points at which material may collect, exhibits good chemical resistance, and permits fabrication of FDA-approved materials such as polyethylene and polypropylene. Provision of three elliptical chute sidewalls, particularly combined with the flat construction of the fourth sidewall, promotes material flow through the discharge chute and reduces the likelihood of material blockage of the discharge chute. The differing sidewall geometries exhibit differing flow characteristics, which in turn greatly reduces any likelihood of material blockage in the chute. A foam sealing gasket is provided around the operator access door on the flat sidewall of the chute to help prevent discharge of dust into the surrounding environment.
The vibrator is secured to the discharge chute by a vibrator mounting plate, which has edge portions secured to inserts molded into the chute sidewall, and a mid portion on which the vibrator is mounted. The mid portion of the bracket is spaced from the chute sidewall so as to permit free circulation of cooling air between the mounting plate and the chute sidewall. Free suspension of the discharge chute within the discharger mounting frame allows free vibration of the chute, further to reduce the likelihood of material blockage at the chute outlet. That is, the discharger body geometry and selection of the material of construction combine to provide an effective method of vibration isolation (suspension) allowing both elimination of vibration isolators and allowing use of a more energy efficient lower horsepower vibrator. An additional steel plate may be mounted between the vibrator mounting plate and plastic discharger body to further distribute stress points and dissipate heat. Molding of the mounting inserts into the chute sidewall, particularly when coupled with the preferred plastic chute material and the method of molding the chute, eliminate cracks, crevices and hollow sections in the chute to prevent collection of material and facilitate acceptance in the food, dairy, pharmaceutical and chemical industries. Multiple mounting points of the vibration mounting plate to the chute reduce plastic fatigue and creep stress around each individual mounting point.